Device for the continuous and automatically controlled driving of warp beams and similar devices bearing a yarn supply

ABSTRACT

Device for continuously and automatically controlling the drive of warp beams and like. A hydraulic motor is provided for driving the warp beam, the motor being under the control of a valve which is operated by a tension sensitive device which detects the tension in the threads being paid off the beam.

United States Patent Dostal 1 1 Dec. 19, 1972 154] DEVICE FOR THE CONTINUOUS AND AUTOMATICALLY CONTROLLED DRIVING OF WARP BEAMS AND SIMILAR DEVICES BEARING A YARN SUPPLY [72] Inventor: Pravomil Dostal, Rychnov nad Kneznou, Czechoslovakia [73] Assignee: Elitex Zavody textilniho strojirenstvi generalni redirelstvi, Liberec, Czechoslovakia [22] Filed: Aug. 19,1970

[21] Appl. No.: 65,114

[30] Foreign Application Priority Data Sept. 5 1969 Czechoslovakia ..6()90/69 [52] US. Cl.....' ..139/ll0, 66/86 A [51] Int. Cl. ..D03d 49/06 [58] Field ofSearch...l39/110, 109, 97, 99; 66/86 A;

[56] References Cited UNITED STATES PATENTS 2.565.386 8/1951 Marcy ..l39/110 1,579,600 4/1926 Durante ..251/2()5 X 3,261.375 7/1966 Berry i t ,.139/1l() 3,221,518 12/1965 Bassist.... ..66/86 2.358.611 9/1944 Ziebolz ..25l/205 X FOREIGN PATENTS OR APPLICATIONS 462,063 10/1968 Switzerland ..139/1 10 594,083 3/1960 Canada ..251/2()5 337,155 4/1959 Switzerland ..l39/l1() Primary ExaminerJames Kee Chi I Attorney-Arthur O. Klein [57] ABSTRACT Device for continuously and automatically controlling the drive of warp beams and like. A hydraulic motor is provided for driving the warp beam; the motor being under the control of a valve which is operated by a tension sensitive device which detects the tension in the threads being paid off the beam.

7 Claims, 2 Drawing Figures INVENTOR I Pravomfl DOST 1 ATTORNEY SHEET 2 0F 2 PATENTED nu: 19 m2 DEVICE FOR THE CONTINUOUS AND AUTOMATICALLY CONTROLLED DRIVING OF WARP BEAMS AND SIMILAR DEVICES BEARING A YARN SUPPLY The present invention relates to a device for the continuous and automatically controlled driving of warp beams and similar yarn supply devices, the purpose of which is reliably to secure the unwinding of warp under constant tension.

Devices serving for maintaining constant the tension of the warp of a loom are of several types; the most widely known types of such devices are those in which the unwinding of warp yarns from the warp beam is performed intermittently by the pull of the warp. The warp beam is braked by suitable means, and the unwinding of the warp threads is helped by a mechanism, which, upon the rising of the warp tension, releases said braking means.

The disadvantage of such known devices consists in the intermittent, irregular motion of the warp beam during the weaving process as a result of changes in the length of the warp in the loom caused by the shedding operation. As a result, the tension of the warp is varied. This causes, as a consequence, a change in the weft density, which manifests itself by strips in the fabric; these become particularly visible upon dyeing the fabric.

Another known device serving for maintaining a constant tension of the warp is made such, that the warp beam is driven by an electric motor through a constant speed transmission. The operation of the electric motor is controlled by a pair of switches controlled by an arm of a movable terminal mounted between them and pressed by a constant force in the direction towards the warp. As the warp tension varies, the arm of the terminal swings out between the switches and thereupon starts and stops the operation of the electric motor.

The latter, second above-described device does not achieve a constant tension of warp, as said tension varies. This is caused by the fact that the electric motor drives the warp beam at a constant velocity, and on the other hand, by the fact that the switches cannot be located as near as possible to the arm of the movable terminal, but that the distance must be adequate to the swinging motion of the arm of the movable terminal upon changing the shed of the loom.

Furthermore, a third device is known in which the warp beam is driven from the main shaft through a mechanism for the continuous change of speed of rotation controlled by means of a hydraulic circuit. In such device, the mechanism for the continuous change of speed of rotation is connected to a piston of a pressure cylinder which is connected to the distributing mechanisms for a pressure fluid; the active part of the distributing mechanism cooperates with the device controlled by the warp tension.

The disadvantage of the last-described device consists in its considerable intricacy in design, and its narrow range of control of the tension, which is given by the range of the ratios of continuous speed variation. Additionally, extreme increases and decreases of tension are compensated only gradually. This manifests itself by a change of the weft density, which causes stripes in the fabric which are particularly visible after dyeing of the resulting fabric.

The said disadvantages of the prior art devices as described above are largely overcome by the device according to the present invention. In accordance with the invention, there is provided a hydraulic motor for driving the warp beam; such hydraulic motor is provided with a control valve which is attached to a feeler of a tension control for sensing the tension of the warp threads.

Further advantages and features of the present invention are further described in the following specification and shown in the accompanying drawings, which illustrate an exemplary embodiment of the invention:

In the drawings:

FIG. 1 is a schematic view showing the manner of connection of the individual elements of the device; and

FIG. 2 is a longitudinal section through the control valve of the system of FIG. 1.

Turning now to FIG. 1, warp threads 1 are unwound from the warp beam 2, guided around cylinders 3 and 4 of the feeler for checking the warp tension, pass through the working points of a loom, including a shed, and are, in the form of a fabric, after being directed by cylinder 5, would onto the cloth beam 6.

The warp beam 2 is mounted in a known manner in the (not shown) side walls of the machine and is driven from the hydraulic motor 8 by means of belt 7 or another suitable transmission. The hydraulic motor 8 is mounted on the side wall of the machine and connected by means of a conduit 9 to pump 10, by means of which the working fluid is pumped from a sump vessel 11 through filter 12 into the hydraulic motor 8. A pressure checking manometer 13 is connected to tube 9, and an overflow tube 14 with an excess pressure relieving valve 15, through which excess working fluid is brought back into vessel 11. Further, the hydraulic motor is connected by conduit 16 to the control valve 17, and through said valve by an overflow conduit 18 with vessel 11. A

The speed of rotation of the hydraulic motor 8, and thus also the velocity at which the warp threads 1 are unwound from the warp beam 2, varies according to the rate of flow of working'fluid passing through the control valve 17. In order to change the speed of rotation of the hydraulic motor 8 as continuously as possible, piston 19 (FIG. 2) which is guided in the body 20 of the control valve 17 is provided on its circumference with an annular groove 21 of sufficient (axial) width as not to close the inlet channel 22, to which conduit 16 from the hydraulic motor 8 is connected, upon transferring piston 19 from its solid line toward its phantom line position shown in FIG. 2. Piston 19 is provided on its circumference with preferably symmetrically distributed longitudinal grooves 23, which start from the annular groove 21, and the cross-section of which becomes narrower in the direction to the right from said annular groove 21. The parts are so dimensioned that even in the extreme right hand position of valve member 19 the annular groove 21 lies to the left of the annular groove 24 in the inner wall of body 20. The length of grooves 23 is thus such that upon transferring piston 19 into its right (phantom line) extreme position the left hand ends of grooves 23 do not confront the annular groove 24. The exit channel 25, to which overflow conduit 18 is connected, connects with annular groove 24, as shown.

The rate of flow of working fluid through the control valve-l7 is changed by adjusting piston 19 longitudinally in the body 20 of the control valve 17. This is performed by the feeler for checking the tension of warp threads 1 acting through a lost motion connection. For that purpose, piston 19 is provided with a threaded piston rod 26, on which are mounted two adjustable abutments, e.g. nuts 27, threadedly engaging the thread on piston rod 26. Between the adjustable abutments 27 there is disposed one arm of a two arm lever 28 of the feeler for checking the tension of warp threads 1. Lever 28 is mounted for free rotation on shaft 29 which carries cylinder 3, and carries on its other arm a rotatably mounted cylinder 4, about which the warp threads 1 are guided. To the lower lever arm there is fastened an elastic element in the form of a coil tension spring. The spring 30 at its other end is fastened to an adjusting screw 31 turning in a nut 32 secured to the side wall of the machine. The screw 31 is turned to stress spring 30 to the degree necessary to produce the desired tension in the warp threads 1. The piston 19 of valve 17 remains stably in itsadjusted longitudinal position until readjusted by the tension sensitive feeler.

The device operates as follows:

The tension of the warp threads 1 is adjusted by the feeler 4, 28 for checking the tension of warp threads 1. This is done by changing the prestress of spring 30 by screw 31, and adjusting the movable abutments 27 in such manner as to locate them a distance apart generally the same as the travel of the lower arm of lever 28 as the two-arm lever 28 of the feeler swings upon change of shed of the loom. The device is now prepared for operation. After starting the machine, upon the first change of the shed in view of the change of tension caused thereupon, the two-arm lever 28 swings about the equilibrium position on two sides, as shown in dashed lines in FIG. 1, thereupon transferring the movable abutments 27 symmetrically with respect to the equilibrium position of the lever. The transfer of the abutments 27 is transmitted by piston rod 26 to piston 19 which takes up a position in the body 20 of control valve 17 in which the right hand ends of longitudinal grooves 23 communicate with the annular groove 24. As a result, working fluid-under-pressure flows through the valve and the hydraulic motor 8 is started. Rotation of the motor is transmitted to the warp beam 2, from which the warp threads 1 are unwound. The lever 28 swings to compensate for changes in the length of the warp in the loom.

When no change of the tension of warp threads 1 takes place, the bent lever 28 swings out upon change of shed between the abutments 27, piston 19 of control valve 17 remaining in an unchanged position, and thus the hydraulic motor 8 and the warp beam 2 remain rotating at the same speed and the speed of unwinding of the warp threads 1 remains the same. If, in that case, the tension of the warp threads is increased for any reason, the two arm lever 28 is swung out into a new equilibrium position to the right from the original position. Its displacement is transmitted by the adjustable abutments 27 and piston rod 26 to piston 19 of control valve 17. The cross-section of the zone of longitudinal grooves 23 immediately communicating with annular groove 24 in the body 20 of control valve 17 is thereby increased, and the working fluid flows through control valve 17 at a faster rate. Thereupon, the speed of rota- Upon a decrease of the tension of threads 1, the two arm lever 28 is swung out from its original position to the left and adjusts piston 19 by means of abutments 27, the cross-section of the zone of the longitudinal grooves 23 immediately communicating with the annular groove 24 is reduced, and the flow of working fluid through control valve 17 is also reduced. The speed of rotation of the hydraulic motor 8 and that of the warp beams 2 decrease. Thus, the warp threads 1 are unwound at a slower speed and their tension is again increased.

Upon a great drop of tension of the warp threads, a large displacement of the two arm lever 28 of the feeler may occur,so thatthe annular groove 24 is closed by piston 19 and thus the unwinding of warp threads 1 from the warp beam 2 is interrupted until their tension is again increased.

It is clear from the above-described embodiment of the device of the invention that the control valve 17 can be connected also in such manner, that the working fluid from the pump 10 is guided into the hydraulic motor 8 through the control valve 17. In such case, the working fluid is withdrawn directly into sump vessel 1 l. The connections and manner of operation of the remaining parts is the same as in the above-described apparatus. The function of the device with control valve 17 connected as a supply valve is the same as that of the illustrated embodiment and is therefore not described.

The device as specified is advantageous because of its simplicity and low manufacturing costs. It is easily adjustable even during operation of the machine, and its parts guarantee that the adjusted values of the warp thread tension do not change for the whole time of the working procedure of the weaving loom.

Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but is capable of numerous modifications within the scope of the appended claims.

What is claimed is:

1. In a loom having a warp beam provided with a yarn supply, a shedding mechanism the operation of which causes a momentary variation in the length of the warp in the loom, and a cloth take-up means, a device for the continuous and automatically controlled drive of the warp beam comprising a hydraulic motor for driving the warp beam, a source of hydraulic fluid under pressure, a control valve for the motor in circuit with the fluid pressure source and the motor, said control valve having a movable valve element, a tension sensitive feeler movable in response to changes in the tension of the warp yarns delivered from the warp beam for controlling the valve, and means connecting thetension sensitive feeler to the movable valve element, said last named means including lost motion means, whereby minor changes inthe tension of the warp yarns delivered from the warp beam caused by the shedding operation do not cause movement of the valve element.

l060ll 0078 2. A device as claimed in claim 1, wherein the feeler for checking the tension of warp yarns has a two-arm lever, one arm of which cooperates with the movable element of the control valve, warp yarns being guided about guide means on the other arm of the lever, and comprising adjustable means for subjecting the lever to a yielding torque whereby to subject the warp yarns to tension.

3. A device according to claim 1, wherein the valve is a throttle valve having a movable valve element which passes fluid at a progressively higher rate as the valve element is moved in one direction.

4. A device according to claim 3, wherein the valve element remains stably in a given adjusted position.

5. A device as claimed in claim 4, wherein the control valve is provided with a control element in the form of a reciprocable piston, the piston has an annular groove therein, the valve body has an annular groove therein, the circumference of the piston having longitudinal grooves therein between the annular groove in the piston and the annular groove in the inner circumference of the body of the control valve, the cross-section of said longitudinal grooves diminishing in the direction from the annular groove in the piston toward the annular groove in the body of the valve.

6. A device as claimed in claim 5 comprising a port in the valve body communicating with the annular groove in the piston in all operative positions of the piston, the maximum length of said longitudinal grooves not exceeding the distance between said port and the annular groove in the body of the valve.

7. A device according to claim 4, comprising means for adjusting the length of the lost motion in the lost motion device.

l060l l 0079 

1. In a loom having a warp beam provided with a yarn supply, a shedding mechanism the operation of which causes a momentary variation in the length of the warp in the loom, and a cloth take-up means, a device for the continuous and automatically controlled drive of the warp beam comprising a hydraulic motor for driving the warp beam, a source of hydraulic fluid under pressure, a control valve for the motor in circuit with the fluid pressure source and the motor, said control valve having a movable valve element, a tension sensitive feeler movable in response to changes in the tension of the warp yarns delivered from the warp beam for controlling the valve, and means connecting the tension sensitive feeler to the movable valve element, said last named means including lost motion means, whereby minor changes in the tension of the warp yarns delivered from the warp beam caused by the shedding operation do not cause movement of the valve element.
 2. A device as claimed in claim 1, wherein the feeler for checking the tension of warp yarns has a two-arm lever, one arm of which cooperates with the movable element of the control valve, warp yarns being guided about guide means on the other arm of the lever, and comprising adjustable means for subjecting the lever to a yielding torque whereby to subject the warp yarns to tension.
 3. A device according to claim 1, wherein the valve is a throttle valve having a movable valve element which passes fluid at a progressively higher rate as the valve element is moved in one direction.
 4. A device according to claim 3, wherein the valve element remains stably in a given adjusted position.
 5. A device as claimed in claim 4, wherein the control valve is provided with a control element in the form of a reciprocable piston, the piston has an annular groove therein, the valve body has an annular groove therein, the circumference of the piston having longitudinal grooves therein between the annular groove in the piston and the annular groove in the inner circumference of the body of the control valve, the cross-section of said longitudinal grooves diminishing in the direction from the annular groove in the piston toward the annular groove in the body of the valve.
 6. A device as claimed in claim 5 comprising a port in the valve body communicating with the annular groove in the piston in all operative positions of the piston, the maximum length of said longitudinal grooves not exceeding the distance between said port and the annular groove in the body of the valve.
 7. A device according to claim 4, comprising means for adjusting the length of the lost motion in the lost motion device. 